It has been normal practice for many years for police officers and other investigators to apply powder, chemicals or other image formers onto various surfaces in search of latent fingerprints, glove prints, footprints, and other evidence or residues. Even though photographs are usually taken of formed images before they are lifted, the images are often "lifted" to preserve the images. The lifted images are often used for forensic study in a crime lab or other site which is remote from the scene where the prints are lifted.
The term "latent" was originally used in describing fingerprints, and the like, which were not clearly visible, but that term is now used on virtually any prints which are left on a substrate other than a print card or other residue made directly from a person or source. A latent print image can be compared with a print card in identifying a person or compared with other images taken directly from a known source.
Latent fingerprints are classified into three categories: those which are visible, e.g., those made by skin covered with other substances such as wet paint, blood, ink, mud; invisible prints left by bare skin in contact with a smooth surface, leaving only a perspiration or natural body oil impression; and plastic prints such as those made on soft substances such as dust, grease, wax, soap, putty, asphalt, and the like. Investigators are familiar with the various types of prints and the manner in which imaged residues of latent prints or other evidence are prepared for lifting by using films or sheets used for that purpose.
Among the various films or sheets used in lifting latent images are tapes having a tacky surface, known as "sticky tapes", or can be metal foil, especially silver foil used in lifting chemical residues, such as those used in lifting iodine fumed prints. Lifting tapes may be transparent, opaque, plastic, paper, and some are sheets, such as sheets of rubber having a sticky surface similar to an innertube patch which has a removable layer covering the sticky surface of the rubber.
Also used are "hinged" lifters which are comprised of three pieces of plastic that are bound on one side by a sheet of paper, one of the plastic sheets having an adhesive substance on one side which is protected by another sheet of plastic, and an outer sheet of plastic which serves as the back of the "book" after lifting. The protective sheet of plastic is removed to reveal the sticky surface for lifting a print, then the protective outer surface is used to cover the lifted print on the sticky surface.
Among the materials used for imaging the latent residues are various powders of very fine particle size, appropriate powders being selected on the basis of type of substrate and darkness of the substrate. Commonly used are very finely grained adhesive compounds, often on an aluminum base. "Dragon's blood", a red powder, is very resilient when heated and is often used.
Fluorescent powders are useful for imaging residues on multicolored surfaces which, when exposed to ultraviolet light in darkness, can be photographed without losing contrast to the multicolored surface.
Means have been developed for lifting images of virtually any latent residue, including gloveprints, shoeprints, and skinprints as well as fingerprints.
As used herein, and for purposes of conciseness, the expression "lifting tape" includes any of the films, foils, tapes, or sheets which are applicable for lifting imaged latent residues from surfaces; "imaged residues" means the same as "imaged latent residues" which are of interest in investigations of the type performed by police officers and other such investigators.
The process of applying a lifting tape normally involves cutting a piece, from a roll or sheet, to a size appropriate for the size of the image to be lifted, carefully smoothing it onto the imaged area while trying to avoid wrinkles or bubbles. Then when the lifting tape is applied to another substrate to preserve it, the operator is again faced with trying to lay it down without having it wrinkle or form bubbles. One difficulty often encountered is that of accurately lifting an imaged residue from a curved surface such as a glass, telephone, club, post, doorknob, pipe, and the like.
It is an object of the present invention to provide a device for applying a lifting tape to an imaged residue in a manner which substantially removes the chances of forming wrinkles or bubbles, especially from curved surfaces, including, e.g., but not limited to, the inside surface of a hollow item such as a bucket, bowl, glass, cup, and the like.
It is further object of the present invention to provide a device which, after lifting of an imaged residue with a lifting tape, can be used to smoothly deposit the lifting tape onto another substrate without encountering wrinkles or bubbles in the lifting tape during the depositing step.